Sinn, a research fellow at the University of Tasmania, observed behaviour in the southern dumpling squid (Euprymna tasmanica), which is found in waters around South Australia, Victoria and Tasmania.

In general, these squid tend to be solitary, unromantic animals with a propensity to cannibalise their neighbours and take sexual favours by force, he says.

Within that profile Sinn found some squid are shy, retiring, cautious types while others are bold, assertive and adventurous.

"It turns out some squid are bolder than others," he says.

"For example, when presented by a threatening stimulus they attack the stimulus or are ambivalent to it.

"Others are shyer, they don't inspect a threat, they back up, they flee."

Assertiveness training for squid

Previous research suggests these character traits in squid are up to 30% hereditary, he says.

But there's evidence that some squid can adapt to their environment by learning to either temper their overconfidence or shake off their shyness.

Sinn says squid and other cephalopods like octopuses and cuttlefish are relatively intelligent and, relative to body size, have brains the size of cats.

This is probably to compensate for the loss of their protective shells during evolution, he says, with more brain capacity needed to protect their vulnerable bodies from predators.

Population dynamics

Sinn says understanding the ecology and evolution of personality provides a key to understanding what drives animal populations.

He says it's unclear which personality traits confer an evolutionary edge, although it appears that having a mix of personalities is essential for a population to survive a disturbance.

"Individual behaviour is going to determine how far [an animal population] disperses, its growth rate, how well it survives and potentially how it reproduces, so all these things are driving population dynamics," he says.

"If you want to know how to predict population abundance maybe we need to know more about individual behaviours and how they're going to react to environmental change."

Squid lovers

Sinn's next project is to investigate the role of personality in the sex life of squid.

He says mating in the squid world is forceful on the part of the male but females play a role in choosing to associate with prospective mates or in attempting to rebuff unwanted advances.

He says early evidence suggests bolder females prefer bolder males while shy females are less choosy.